Three-dimensional display techniques may include a glass type three-dimensional display technique and a glass-free type three-dimensional display technique. As compared with the glass type three-dimensional display technique, the glass-free type three-dimensional display technique more satisfies peoples' requirements. Except glass type three-dimensional display products used in cinemas, most three-dimensional display products use glass-free three-dimensional display products. A display device based on the glass-free display technique is generally formed of a two-dimensional (2D) display screen and three-dimensional (3D) optical grating. The 2D display screen may be a liquid crystal display or an organic light emitting diode (OLED) display, and the 3D grating may be a stationary metal grating, a resin grating, or a liquid crystal grating. The liquid crystal grating has better operability, and is more advantageous over the stationary metal grating.